1. Field of the Invention
The invention relates to a heat dissipating device, more particularly to a heat dissipating device which includes a pressing member that is rotatable to urge a fin module toward a circuit board.
2. Description of the Related Art
FIG. 1 illustrates a conventional heat dissipating device for dissipating heat generated by an electronic component 63, such as a central processing unit, that is mounted on a circuit board 64. The conventional heat dissipating device includes a base frame 65 mounted on the circuit board 64, a heat-dissipating fin module 62 disposed in the base frame 65, and a fan module 6 mounted on the base frame 65 and disposed above the fin module 62. The base frame 65 has a bottom part formed with a through hole 653 that is registered with the electronic component 63 so as to allow the electronic component 63 to extend thereinto when the base frame 65 is mounted on the circuit board 64, and opposite flange members 651 extending respectively and upwardly from sides of the bottom part that are opposite in a first direction. Each of the flange members 651 is formed with a pair of engaging holes 652 that are spaced apart from each other in a second direction transverse to the first direction. The fin module 62 is disposed on the bottom part and is in heat-conductive contact with the electronic component 63. The fin module 62 has a plurality of parallel fin plates 620. The fan module 6 includes a positioning seat 66 disposed above the fin plates 620, a fan 61 mounted on the positioning seat 66, and parallel positioning members 67. The positioning seat 66 has opposite downwardly extending side walls 661 for positioning the fin plates 620 therebetween, and a pair of upwardly opening positioning grooves 662 that are spaced apart from each other in a second direction. The positioning seat 66 is formed with a through hole 663 so as to allow air currents from the fan 61 to reach the fin plates 620. Each of the positioning members 67 has a positioning piece 671, an engaging piece 672 opposite to the positioning piece 671, and a downwardly extending intermediate positioning block 673 that is disposed in a respective one of the positioning grooves 662 of the positioning seat 66. When the fan module 6 is assembled onto the base frame 65, first, the positioning piece 671 of each of the positioning members 67 engages a respective one of the engaging holes 652 in one of the flange members 651, and the engaging piece 672 of each of the positioning member 67 is then pressed downwardly to engage a respective one of the engaging holes 652 in the other one of the flange members 651.
However, when the positioning pieces 671 of the positioning members 67 do not engage the engaging holes 652 in one of the flange members 651 at the same time, a pressure difference is formed at one side of the fin module 62 so as to result in tilting of the same. As such, different pressures applied by the positioning members 67 may result in damage to the electronic component 63 and have an adverse affect on the mounting efficiency.
Therefore, the object of the present invention is to provide a heat dissipating device with a heat-dissipating fin module that can be mounted easily and evenly on a circuit board.
According to the present invention, a heat dissipating device is adapted to a circuit board for dissipating heat produced by an electronic circuit board, and comprises:
a base frame adapted to be mounted on the circuit board and including a bottom part with first and second sides opposite to each other in a first direction, each of the first and second sides having first and second flange members that extend upwardly from the respective side and, each flange is formed with a respective engaging hole spaced apart from the other engaging hole in a second direction transverse to the first direction, the bottom part being formed with a through hole that is registered with the electronic component so as to allow the electronic component to extend thereinto when the base frame is mounted on the circuit board;
a heat-dissipating fin module disposed in the base frame on the bottom part and adapted to be in heat-conductive contact with the electronic component, that fin module having a plurality of parallel fin plates, adjacent ones of the fin plates being spaced apart from each other; and
a fan module mounted on the base frame and disposed above the fin module, the fan module including
a fan for inducing air currents between each adjacent pair of the fin plates,
parallel positioning members connected to the fan and spaced apart from each other in the second direction, each of the positioning members having a positioning end portion, a coupling end portion opposite to the positioning end portion, and an intermediate abutting portion disposed between the positioning and coupling end portions and extending in the first direction above the fin module, the positioning end portion being formed with a positioning piece that engages a respective one of the engaging holes in one flange member on the first side of the bottom part of the base frame, and
an operating member extending in the second direction and coupled pivotally to the coupling end portions of the positioning members, the operating member having opposite engaging end portions and an intermediate pressing portion between the engaging end portions, the pressing portion being operable so as to rotate the engaging end portions relative to the fan from a disengaging position, where the engaging end portions disengage the engaging holes in the flange member on the second side of the bottom part of the base frame such that the abutting portions of the positioning members are relieved from applying pressure on the fin module, to an engaging position, where each engaging end portion engages a respective engaging hole in the flange member on the second side of the bottom part of the base frame such that the abutting portions of the positioning members are pulled toward and apply pressure on the fin module, thereby enabling the fin module to contact tightly the electronic component.